standOff, and the article is at its publisher via the link below. When we have changed our mind. Some entries in the table begin with a word in capitals and the reason for it. EVIDENCE CORRECTED — the finding still stands, but we had quoted the wrong sentence from the paper, and the quotation has been replaced with the right one. RETRACTED — the entry itself was wrong; it stays on the page, marked, with the reason, rather than being deleted. WITHDRAWN AND REPLACED — the entry was wrong, and a corrected version of it appears in the entries below. Each mark carries its own reason, in brackets, because the reasons differ from one entry to the next. An entry we have WITHDRAWN is removed from this page and kept in the record, with its reason. A line reading Audit and a date is a later re-reading of the entry against its whole sentence: DOUBTFUL means it was kept, and the reason says what is loose about it. Quotation marks inside the tagger's sentence. Where a tag is the tagger's own sentence, a phrase in quotation marks inside it is borrowed from the paper — the tagger's wording around it is not. The paper's own sentence is the evidence quote for that row; on this page it is withheld with the article, and the article is at its publisher. Nothing inside quotation marks anywhere on this page is ours: if it is quoted, it is the paper's. Whose words a concept carries. A concept entry records a term the paper itself uses, so the term, the sense given for it, and its evidence are the paper's own words, quoted where the paper fixes them. This is the opposite of a sense entry in the tag table, which is the tagger's sentence about how the paper uses a term. Where a concept entry could not be grounded in the paper's words, the entry says so on its own row.| relation to other work | claim_relations | how this paper stands to another: agrees, contradicts, extends, qualifies |
| claim type | claim_type | the shape of the claim: existence, mechanism, method, critique, prediction, null |
| concept | concepts | an idea the paper works with, quoted where the paper uses it |
| content tag | content_tags | a finding, definition, quantity, statistic or variable named in the paper |
| contribution | contribution | what the paper claims to add |
| control | controls | an experiment run to eliminate a rival explanation |
| limitation | limitations | what the paper says its evidence cannot support |
| mechanism | mechanisms | how the reported effect is said to come about |
| method | method | how the paper produced its evidence |
| object of study | object_of_study | what the paper is about — the thing it investigates |
| phenomenon | phenomenon | the effect or regularity under study |
| research question | research_question | the question the paper sets itself |
| sense | senses | a distinct use of a term, quoted where the paper fixes it |
| transfer | transfers | a method or concept carried in from another field |
This record holds no relations between concepts. A layer is empty when the tagger recorded nothing in it — which is not the same as the paper having nothing to record.
| facet | tag | field | conf. | whose words |
|---|---|---|---|---|
| object_of_study | serum concentrations of twelve polyfluoroalkyl chemicals in a representative sample of the U.S. population aged 12 and over Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | object_of_study | the paper's words | |
| research_question | whether U.S. population exposure to PFCs changed after the 2002 discontinuation of PFOS production Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | research_question | the paper's words | |
| contribution | the first nationally representative PFC serum estimates after the manufacturing change, with a method-equivalence check spanning the two survey waves Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | contribution | the paper's words | |
| claim_type | existence Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | claim_type | the paper's words | |
| phenomenon | population-wide, measurable exposure to persistent fluorinated chemicals, declining for three compounds and rising for one Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | phenomenon | the paper's words | |
| method | observational-study Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: observational-study | method | the paper's words | |
| mechanisms | electrochemical fluorination of PFOS and related compounds stopped in 2002, and three of the four common PFCs show lower geometric means four years later Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | mechanisms[0] | 0.95 | the tagger's words |
| mechanisms | PFHxS declines least because it clears slowest - 7.3 years against 4.8 for PFOS and 3.5 for PFOA - so the same phase-out shows up later in it Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: differential elimination half-life | mechanisms[1] | 0.95 | the tagger's words |
| mechanisms | PFOS and PFOA correlate more strongly with each other than either does with PFHxS, which the authors read as a shared source that PFHxS does not have Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: separate formation pathways | mechanisms[2] | 0.85 | the tagger's words |
| mechanisms | PFHxS is higher in adolescents than adults, and the proposed reason is contact with carpets treated with it - a route specific to one compound Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: childhood carpet contact | mechanisms[3] | 0.85 | the tagger's words |
| limitations | PFNA doubled, and the authors say human exposure data for it are too limited to interpret the rise confidently Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | limitations[0] | 0.95 | the tagger's words |
| limitations | for the two rarest analytes no 95th percentile could be calculated at all Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | limitations[1] | 0.95 | the tagger's words |
| limitations | no definite association between PFOS or PFOA exposure and adverse health effects has been established in humans Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | limitations[2] | 0.95 | the tagger's words |
| limitations | the animal effects that motivate concern occur at serum concentrations orders of magnitude above those measured here Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | limitations[3] | 0.95 | the tagger's words |
| transfers | the persistent-organic-pollutant framework, carried from chlorinated chemicals to fluorinated ones, including the expectation that concentrations rise with age - which fails here Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | transfers[0] | 0.95 | the tagger's words |
| controls | 124 split samples run through BOTH analytical methods, to test whether the method change between survey waves produced the trend Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: a fall in serum concentrations that is a change of analytical method between survey waves - the split samples make the two methods comparable on the same serum · outcome: held | controls[0] | 0.95 | the tagger's words |
| controls | the explicit question of whether the decline is an artefact of changed methodology Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: the same artefact, asked as a question of the result rather than of the instrument · outcome: held | controls[1] | 0.95 | the tagger's words |
| controls | calibration standards spiked into calf serum to account for matrix effects and the absence of labelled internal standards for most analytes Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: a systematic bias from the serum matrix, or from the absence of an isotope-labelled internal standard for most analytes, being read as a concentration difference · outcome: held | controls[2] | 0.95 | the tagger's words |
| controls | low- and high-concentration quality-control pools run alongside reagent blank, serum blank and the samples Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: analytical drift across a run being reported as variation between people · outcome: held | controls[3] | 0.95 | the tagger's words |
| controls | agreement of the declines with independent series - Red Cross blood donors and Arctic ringed seals Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: a decline confined to this survey's sampling frame - the seals and the blood donors share no methodology and no population with NHANES · outcome: held | controls[4] | 0.95 | the tagger's words |
| controls | confounding, tested by re-adding each excluded variable and watching the beta coefficients Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: a coefficient that survives only under the authors' final choice of covariates · outcome: held | controls[5] | 0.95 | the tagger's words |
| controls | the split-sample comparison for analytes other than PFOA Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: that the change in concentrations between survey rounds is a change in analytical method - answered for PFOA and left unshown for the other analytes · outcome: partial | controls[6] | 0.95 | the tagger's words |
| controls | emission-reduction efforts for PFNA, the one compound that rose Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: an emissions explanation for the one compound that ROSE - the reduction efforts that would provide it were looked for and not found, which the paper says · outcome: absent-declared-unreported | controls[7] | 0.95 | the tagger's words |
| concepts | limits of detection Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: limits of detection | concepts[0] | 0.95 | the paper's words |
| concepts | geometric mean Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: geometric mean | concepts[1] | 0.95 | the paper's words |
| concepts | Biomonitoring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Biomonitoring | concepts[2] | 0.85 | the paper's words |
| concepts | serum cotinine Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: serum cotinine | concepts[3] | 0.95 | the paper's words |
| concepts | split samples Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: split samples | concepts[4] | 0.95 | the paper's words |
| concepts | PFBuS Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: PFBuS | concepts[5] | 0.95 | the paper's words |
| concepts | lipophilic POPs Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: lipophilic POPs | concepts[6] | 0.95 | the paper's words |
| concepts | half-life Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: half-life | concepts[7] | 0.85 | the paper's words |
| senses | a NON-DETECT is entered as LOD divided by the square root of 2 - imputed, not measured Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[0] | 0.95 | the tagger's words |
| senses | a mean is REPORTABLE only where the analyte was detected in at least 60% of samples Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[1] | 0.95 | the tagger's words |
| senses | a SMOKER is anyone with serum cotinine above 10 ug/L - a biomarker threshold, not self-report Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[2] | 0.95 | the tagger's words |
| senses | RACE/ETHNICITY is three self-reported categories, and everyone else is counted in the total but excluded from every subgroup comparison Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[3] | 0.95 | the tagger's words |
| senses | a CONFOUNDER is a variable whose re-addition moves a beta coefficient by 10% or more Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[4] | 0.95 | the tagger's words |
| senses | a RETAINED model term is one surviving backward elimination at p < 0.05 Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | senses[5] | 0.95 | the tagger's words |
| claim_relations | extends → the NHANES 1999-2000 PFC serum concentrations reported by the same group Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. note: the same survey, the same laboratory, four years later, and the comparison is the paper's point | claim_relations[0] | the tagger's words | |
| claim_relations | confirms → reported reductions in PFOS and PFOA in Red Cross blood donors and in Arctic ringed seals Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. note: independent populations and an independent species moving the same way over the same interval | claim_relations[1] | the tagger's words | |
| content_tags | Apparent reductions in PFOS, PFOA and PFHxS most likely relate to the 2002 end of electrochemical-fluorination production. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.findings[0] | 0.95 | the tagger's words |
| content_tags | unlike lipophilic persistent organic pollutants, these PFCs do not accumulate with age Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.findings[1] | 0.95 | the tagger's words |
| content_tags | PFBuS was detected less often than PFOS, PFOA and PFHxS. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.findings[2] | 0.95 | the tagger's words |
| content_tags | the two analytical methods agreed on 124 split samples, so the trend is not a method artefact Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.findings[3] | 0.95 | the tagger's words |
| content_tags | limits of detection Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: limits of detection | content_tags.definitions[0] | 0.95 | the tagger's words |
| content_tags | smokers Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: smokers | content_tags.definitions[1] | 0.95 | the tagger's words |
| content_tags | Race/ethnicity Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Race/ethnicity | content_tags.definitions[2] | 0.95 | the tagger's words |
| content_tags | PFOS, PFOA, PFHxS and PFNA detected in over 98% of 2,094 samples — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. value source note: THE VALUE DRAWS ON THE PAPER BEYOND THIS QUOTE: part of it is printed elsewhere in the paper, not in this quote ('of 12 PFCs, including PFOS and PFOA, in 2,094 participants…'). | content_tags.quantities[0] | 0.95 | the tagger's words |
| content_tags | limits of detection 0.1 to 1.0 ug/L; accuracy 84 to 135%; precision about 10 to 26% — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.quantities[1] | 0.95 | the tagger's words |
| content_tags | EVIDENCE CORRECTED (RE-GROUNDED - THE POINTER WAS WRONG, NOT THE CLAIM) · geometric means down about 32% for PFOS, 25% for PFOA, 10% for PFHxS; PFNA up 100% — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. EVIDENCE CORRECTED: RE-GROUNDED - THE POINTER WAS WRONG, NOT THE CLAIM. The old evidence was verbatim, anchored and correctly cut, and it contained NONE of this claim's numbers (10, 100, 25, 32). The paper states the claim in one sentence elsewhere and the tagger did not use it. the project, 2026-08-23: 'WE HAVE SPENT THE DAY VERIFYING THAT QUOTES ARE REAL AND NONE OF IT ASKS WHETHER THEY ARE RELEVANT.' Confirmed by reading the claim, the old span and the candidate together; the candidate carries every number AND the claim's own content words. | content_tags.quantities[2] | 0.95 | the tagger's words |
| content_tags | serum elimination half-lives: PFHxS 7.3 years, PFOA 3.5, PFOS 4.8 — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.quantities[3] | 0.95 | the tagger's words |
| content_tags | PFNA ammonium salt production 15-75 tonnes in 2004; PFOA emissions about 15 tonnes, down from 45 in 1999 — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.quantities[4] | 0.95 | the tagger's words |
| content_tags | smoking threshold: serum cotinine above 10 ug/L — None Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.quantities[5] | 0.95 | the tagger's words |
| content_tags | geometric mean of a log-transformed, survey-weighted distribution Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.statistics[0] | 0.95 | the tagger's words |
| content_tags | backward elimination at p < 0.05 with Satterwaite adjusted F statistics Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.statistics[1] | 0.95 | the tagger's words |
| content_tags | detection frequency threshold of 60% for parametric statistics Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. | content_tags.statistics[2] | 0.95 | the tagger's words |
| content_tags | serum cotinine Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: serum cotinine | content_tags.variables[0] | 0.95 | the tagger's words |
| content_tags | geometric mean Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: geometric mean | content_tags.variables[1] | 0.95 | the tagger's words |
Tags that could not be placed in the text:
What was deliberately not tagged, and why, is recorded per paper by the tagger. Where a paper has no such record, this page says so rather than implying that nothing was declined.